1. Field of the Invention
This invention relates to arithmetic processors and, in particular, to a novel and highly effective arithmetic processor adapted for use in video image processors and in other high-speed data processors and able to process data more rapidly than arithmetic processors heretofore conventional in such apparatus.
2. Description of the Prior Art
Video image processing apparatus must process data at high speed. In commercial television, for example, 25 or 30 frames (depending on the system) are displayed per second, each frame including hundreds of lines and each line including hundreds of pixels (picture elements). In advanced image processing apparatus, signals produced by a television camera are typically converted to digital form, stored in an input image memory, processed in a position stationary processor, stored in an output image memory, converted back to analog form, and then recorded by a VTR and/or displayed on a television monitor. Apparatus such as a position variant processor, a control processor and a host computer are provided for controlling data flows, controlling the execution and stopping of processes, and controlling the entire video image processing apparatus.
In such apparatus, the position stationary processor includes a number of arithmetic units that process signals consisting of data signals and a coefficient. Each data signal is multiplied by its coefficient to produce an output. Depending on the magnitude of the signals, the multiplication requires in conventional practice a different number of steps, for example three to five. It is difficult to write a program that infallibly takes the difference in the number of processing steps (and hence in processing time) into account. Typically, therefore, the program allows for the maximum number of steps that may be required, for example five steps. This means that time is wasted in any case where only three or four steps are required for the multiplication. While the time wasted is short in any given instance, the wasted time is accumulated over and over and is quite significant in the aggregate.